Proteinuria is a medical term for protein found in the urine. It usually is picked up by a screen test called dipstick in the doctor's office. It is registered as negative, trace, and positive from + to ++++. Normally you should only have negative to trace protein on a urine dipstick.
Each kidney contains hundreds of thousands of mini-filters called nephrons. Kidneys remove waste, salts and excess water in the form of urine but not protein. Normally children have only a very small amount of protein in their urine. Proteinuria can be transient, orthostatic or persistent. Transient protienuria is caused by fever or other stresses like heavy exercise. Orthostatic proteinuria happens when one changes position from lying down to standing. Transient and orthostatic proteinuria are the most common ones in children. Those are benign conditions. Persistent proteinuria occurs when the integrity of the nephrons gets disrupted, either due to congenital defect, or inflammation in the form of glomerulonephritis (link) or nephrotic syndrome (link). Persistent protienuria requires careful evaluation by a nephrologist and long term follow up.
Children with proteinuria can be completely asymptomatic depending on the amount of the protein lost in their urine and the underlying causes. For children with heavy proteinuria, they can have swelling in the face, legs or abdomen. Some patients may have elevated blood pressure.
For children referred to our office for proteinuria, they might get some additional urine and blood tests. A first morning urine study is helpful to distinguish orthostatic protienuria from others. When transient proteinuria is suspected, urine should be checked when the stresses subside. For persistent proteinuria, a kidney biopsy might be indicated to help determine possible causes and guide treatments.
Transient and orthostatic proteinuria do not require treatment. For persistent protienuria, treatment has to be determined by the underlying causes. Some patients may require certain medications to control the inflammation. Most common ones used are steroids or certain blood pressure medications. Some children with heavy proteinuria require a low sodium diet, especially when they become puffy.